Inline piston pump

ABSTRACT

An inline piston pump that is efficient, manufacturable, and durable. The angled bearing surface within the pump that it contacts drives the piston and rotates with the cylinder.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Indian Provisional PatentApplication No. 202011030087, filed on Jul. 15, 2020, the disclosure ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure provides an inline piston pump.

BACKGROUND

Inline piston pumps are used for pumping hydraulic fluids. Piston pumpsare used in a wide range of industries and applications. For example,they are used in the aerospace industry to deploy and retract thelanding gear of an airplane. Inline piston pumps work by includingmultiple pistons in a cylinder that suck in fluid from a low-pressureinlet and deliver it to a high-pressure outlet. As the cylinder rotates,the pistons are driven against an angled plate that causes the pistonsto reciprocate. Typically, the angled plate does not rotate with thecylinder. The ends of the pistons include shoes that contact and slidealong the non-rotating angled plate. The interface between the angledplate and the piston is prone to wear. The shoes are typicallyconstructed of a bronze end portion on a ball joint and include ahydrostatic pad to reduce wear. The hydrostatic pads act as a leakagepath for the fluid reducing the volumetric efficiency of the pump.

Some efforts have been made to redesign traditional inline piston pumpsto avoid reliance on expensive and difficult to manufacture shoes whichintroduce mechanical and hydraulic inefficiencies. For example, see U.S.Pat. Nos. 6,036,374; 4,741,251; 7,941,998; 9,624,914; WO2006122642;CN2649802; and JP3781908, which are all herein incorporated by referencein their entireties. Known inline piston pump configurations that do nothave traditional piston shoes have their own challenges and drawbacks.Therefore, there continues to be a need for advancement in the inlinepiston pump's design. Pumps with higher efficiency, longer life, andless cost and complexity in its manufacture are desired.

SUMMARY

The present disclosure provides an inline piston pump that is efficient,manufacturable, and durable. In the depicted embodiment, the angled yokeassembly within the pump that contacts and drives the pistonsynchronously rotates with the cylinder.

BRIEF DESCRIPTION OF THE FIGURES

The following drawings are illustrative of particular embodiments of thepresent disclosure and therefore do not limit the scope of the presentdisclosure. The drawings are not to scale and are intended for use inconjunction with the explanations in the following detailed description.Embodiments of the present disclosure will hereinafter be described inconjunction with the appended drawings, wherein like numerals denotelike elements.

FIG. 1 is an isometric view of an embodiment of the pump according tothe principles of the present disclosure;

FIG. 2 is an exploded assembly view of the pump of FIG. 1;

FIG. 3 is a cross-sectional view of the pump of FIG. 1 in a firstposition;

FIG. 4 is a cross-sectional view of the pump of FIG. 1 in a secondposition;

FIG. 5 is a cross-sectional view of the pump of FIG. 1 in a thirdposition;

FIG. 6 is an isometric view of the pistons, yoke assembly, and cylinder(similar to what is shown below);

FIG. 7 is an isometric view of the piston and yoke assembly;

FIG. 8 is an exploded assembly view of the yoke assembly;

FIG. 9 is a cross-section of a portion of the pump of FIG. 1;

FIG. 10 is an isometric view of a piston of the pump of FIG. 1;

FIG. 11 is a cross-sectional view of the piston of FIG. 10;

FIG. 12 is an isometric view of the dial plate of the pump of FIG. 1;

FIG. 13 is a top view of the dial plate of FIG. 12;

FIG. 14 is a cross-sectional view of the dial plate of FIG. 12;

FIG. 15 is an isometric view of the bearing plate of the pump of FIG. 1;

FIG. 16 is a top view of the bearing plate of FIG. 15 with the contactpath with the pistons shown in dashed lines; and

FIG. 17 is an isometric view of the cylinder block of the pump of FIG.1.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate embodiments of the invention, and such exemplifications arenot to be construed as limiting the scope of the invention in anymanner.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentdisclosure, examples of which are described herein and illustrated inthe accompanying drawings. While the invention will be described inconjunction with embodiments, it will be understood that they are notintended to limit the invention to these embodiments. On the contrary,the invention is intended to cover alternatives, modifications, andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims.

Referring to the figures, the pump of the present disclosure isdescribed in further detail. In the depicted embodiment, the pump 10includes a housing 12. In the depicted embodiment, the housing 12includes a first end portion 14 and a second end portion 16. The firstend portion 14 includes a low-pressure fluid inlet 18 and ahigh-pressure fluid outlet 20. It should be appreciated that manyalternative housing configurations are possible. It should also beappreciated that the same technology described and shown herein can beused for a hydraulic motor.

The pump 10 of the depicted embodiment includes a cylinder block 22rotatably positioned within the housing 12. In the depicted embodiment,the cylinder block 22 includes a first end portion 24 and a second endportion 26. The first end portion 24 of the cylinder block 22 ispositioned in the first end portion 14 of the housing 12. The second endportion 26 of the cylinder block 22 is positioned in the second endportion 16 of the housing 12. In the depicted embodiment, the cylinderblock 22 includes a plurality of cylindrical bores 28, 30 that extendfrom the first end portion 24 to the second end portion 26 of thecylinder block 22. It should be appreciated that many alternativecylinder block configurations are possible.

In the depicted embodiment, the pump 10 includes a drive shaft 32 thatincludes a first end portion 34 that extends inside of the housing 12and is configured to drive the rotation of the cylinder block 22 withinthe housing 12. The drive shaft 32 defines a cylinder block axis ofrotation CBAR (see FIG. 9). In the depicted embodiment, the drive shaft32 is integral with the cylinder block 22. It should be appreciated thatmany alternative drive shaft configurations are possible (e.g., thedrive shaft can be separable from the cylinder block and splined to thecylinder block).

In the depicted embodiment, the pump 10 includes a plurality of pistons36, 38. Each piston 36, 38 includes a first end portion 40 and a secondend portion 42. Each piston 36, 38 is positioned within a cylindricalbore 28, 30 such that the piston 36, 38 can reciprocate within thecylindrical bore 28, 30 axially along the longitudinal axis of thepiston 36, 38. The first end portions 40 of the pistons 36, 38 arepositioned in the first end portion 24 of the cylinder block 22. Thesecond end portions 42 of the pistons 36, 38 extend out of the secondend portion 26 of the cylinder block 22. It should be appreciated thatmany alternative piston configurations are possible.

In the depicted embodiment, the second end portion 42 of the pistons 36,38 includes a conical head portion that includes a conical distal end 68with an annular wall 70 that forms a central point 72. In the depictedembodiment, the annular wall 70 is curved (e.g., elliptical cone,parabolic cone, etc.). In the depicted embodiment, if the second endportion 42 is tilted with respect to the bearing plate 48 such that theannular wall 70 contacts the bearing plate 48, only a small area of theannular wall 70 is in direct contact with the bearing plate 48 since theannular wall 70 is not straight. In the depicted embodiment, the backedge portion 74 of the cone forms an annular collar that has a largerdiameter than the diameter of the other portions of the pistons 36, 38.In the depicted embodiment, the annular collar is a retaining collarthat interfaces with a retainer 50 to limit axial movement of thepistons 36, 38. The retainer 50 will be described in further detailbelow. It should be appreciated that many alternative configurations ofthe pistons' second end portions are possible.

In the depicted embodiment, the pump 10 includes an angled yoke assemblylocated in the second end portion 16 of the housing 12. In the depictedembodiment, the yoke assembly is inclined relative to a plane that isperpendicular to the cylinder block axis of rotation CBAR. In thedepicted embodiment, the yoke assembly includes a bearing surface BSconfigured to contact the second end portions 42 of the plurality ofpistons 36, 38. In the depicted embodiment, the bearing surface BS ofthe yoke assembly is configured to rotate about a yoke assembly axis ofrotation YAAR (coincident with the angled plate axis of rotation APAR)synchronously with the cylinder block 22. It should be appreciated thatmany alternative configurations of the angled yoke assembly arepossible.

In the depicted embodiment, the yoke assembly axis includes an angledplate 44 that rotates on a bearing assembly 46. In the depictedembodiment, the yoke assembly also includes a bearing plate 48 thatinterfaces with the angled plate 44. These components of the yokeassembly of the present disclosure are described in further detailbelow. It should be appreciated that the angled yoke assembly inalternative embodiments may include more, less, and/or differentcomponents than are depicted herein.

In the depicted embodiment, the pump 10 includes an angled plate 44located in the second end portion 16 of the housing 12. The angled plate44 is inclined relative to a plane that is perpendicular to the cylinderblock axis of rotation CBAR. In the depicted embodiment, the angle isfixed and set by the annular shim 64. In the depicted embodiment, therotational speed of the drive shaft 32 varies in order to vary the flowof the pump 10 as desired. In the depicted embodiment, the rotationalspeed of the drive shaft 32 can vary from zero to over ten thousandrotations per minute. In addition, the direction of rotation can alsovary. It should be appreciated that many alternative embodiments of theangled plate are possible. For example, in an alternative embodiment,the angle of the angled plate 44 could be adjustable.

In the depicted embodiment, the pump 10 includes a bearing assembly 46provided between the angled plate 44 and the second end portion 16 ofthe housing 12. The bearing assembly 46 enables the angled plate 44 torotate about an angled plate axis of rotation APAR (See FIG. 9). In thedepicted embodiment, an intersection point IP that is defined as theintersection of the projection of the cylinder block axis of rotationCBAR and the projection of the angled plate axis of rotation APAR iswithin the plane P1 defined by a top surface of the retainer 50 and theplane P2 bottom surface of the retainer 50. It should be appreciatedthat many alternative configurations of the bearing assembly arepossible.

In the depicted embodiment, the angled plate axis of rotation APARintersects with a bearing surface plane BSP that is coincident with anexposed face of the bearing plate 48 at a bearing plate central pointBPCP that is offset from the intersection point IP between the angledplate axis of rotation APAR and the cylinder block axis of rotationCBAR. In the depicted embodiment, the offset between the bearing platecentral point BPCP and the intersection point IP between the angledplate axis of rotation APAR and the cylinder block axis of rotation CBARis in the direction of the second end portion 16 of the housing 12 andalong the angled plate axis of rotation APAR. In the depictedembodiment, the bearing plate central point BPCP is offset from thecylinder block axis of rotation CBAR. In the orientation shown in FIG.9, the bearing plate central point BPCP is offset in a direction belowthe cylinder block axis of rotation CBAR. It should be appreciated thatmany alternative configurations are possible.

In the depicted embodiment, the pump 10 includes a bearing plate 48 thatis secured to the angled plate 44. The bearing plate 48 is configured tocontact with the second end portion 42 of the plurality of pistons 36,38. In the depicted embodiment, the bearing plate 48 has a washer shape,and is received (e.g., pressed into) into a recess on the angled plate44 thereby constraining its movements. In one embodiment, a pin 62 isreceived in the angled plate 44 and engages a recess in the bearingplate 48 to further limit movement of the bearing plate 48 relative tothe angled plate 44. In the depicted embodiment, the pin 62 canconstrain relative rotation between the bearing plate 48 and the angledplate 44 (see FIG. 3). It should be appreciated that many alternativeconfigurations of the bearing plate are possible. For example, in analternative embodiment, the bearing plate 48 is an integral surface ofthe angled plate 44 rather than a separable component part.

In the depicted embodiment, the pump 10 includes a retainer 50configured to engage the second end portions 42 of the pistons 36, 38and limit the axial motion of the pistons 36, 38. In the depictedembodiment, the angled plate 44, the bearing plate 48, and the retainer50 are configured to rotate with the cylinder block 22. In the depictedembodiment, the retainer 50 is a plate that includes a plurality ofouter apertures 52 arranged in circle around a central aperture 54. Thesecond end portions 42 of the pistons 36, 38 extend through the outerapertures 52 and the drive shaft 32 extends through the central aperture54. In the depicted embodiment, the retainer 50 is bolted to the angledplate 44. In the depicted embodiment, the retainer 50 includes threeperiphery apertures 56 that are equally spaced apart that receive bolts58 that secure the retainer 50 onto raised mounting locations 60 of theangled plate 44. In the depicted embodiment, the raised mountinglocations 60 are sized such that the retainer 50 when secured to theangled plate 44 constrains the pistons 36, 38 axially yet allows forrelative movement of the pistons 36, 38 and the bearing plate 48. Inoperation, the second end portion 42 of the pistons 36, 38 are driveninto contact with the bearing plate 48 during the compression/dischargestroke. The retainer 50 limits the amount the second end portions 42 ofthe pistons 36, 38 can axially separate from the bearing plate 48 duringthe suction/intake stroke. The limited axial movement provided by theretainer 50 minimizes the impact forces that the second end portions 42of the pistons 36, 38 impart on the bearing plate 48. In the depictedembodiment, the longitudinal central axis of the pistons 36, 38translates radially relative to the bearing plate 48 as the cylinderblock 22 rotates about its axis. In the depicted embodiment, the pointof contact between the second end portions 42 of the pistons 36, 38 andthe bearing plate 48 during a full rotation of the cylinder traces anelliptical circle 66 on the bearing plate 48. In the depictedembodiment, the retainer plate limits the relative axial motion betweenthe pistons 36, 38 and the bearing plate 48. It should be appreciatedthat many alternative embodiments of the retainer are possible.

In the depicted embodiment, the second end portions 42 of the pistons36, 38 do not radially displace about the cylinder block axis ofrotation CBAR relative to a stationary bearing plate 48. The bearingplate 48 rotates with the cylinder block 22 thereby minimizing relativedisplacement between the second end portions 42 of the pistons 36, 38.The cylinder block 22 and the bearing plate 48 rotate synchronously. Theconfiguration also minimizes friction between the pistons 36, 38 and thebearing plate 48. This configuration prolongs the working lifespan ofthe pump 10. Additionally, minimizing friction increases the efficiencyof the pump 10. In the depicted embodiment, the second end portion 42 ofthe pistons 36, 38 is constructed of hardened tool steel and the bearingplate 48 is also constructed of hardened tool steel. It should beappreciated that many alternative constructions are also possible.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the claimsattached hereto. Those skilled in the art will readily recognize variousmodifications and changes that may be made without following the exampleembodiments and applications illustrated and described herein, andwithout departing from the true spirit and scope of the followingclaims.

What is claimed is:
 1. An axial piston device comprising: a housingincluding a first end portion and a second end portion and including alow-pressure fluid inlet and a high-pressure fluid outlet at the firstend portion of the housing; a cylinder block rotatably positioned withinthe housing including a first end portion and a second end portion, thefirst end portion of the cylinder block being in the first end portionof the housing and the second end portion of the cylinder block being inthe second end portion of the housing, the cylinder block including aplurality of cylindrical bores that extend from the first end portion tothe second end portion of the cylinder block; a drive shaft including afirst end portion that extends inside of the housing and is configuredto drive the rotation of the cylinder block within the housing, thedrive shaft defining a cylinder block axis of rotation; a plurality ofpistons, each piston including a first end portion and a second endportion, each piston being positioned within a cylindrical bore suchthat the piston can reciprocate within the cylindrical bore axiallyalong a longitudinal axis of the piston, the first end portion of thepistons being positioned in the first end portion of the cylinder block,and the second end portion of the pistons extending out of the secondend portion of the cylinder block; and an angled yoke assembly locatedin the second end portion of the housing, the yoke assembly beinginclined relative to a plane that is perpendicular to the cylinder blockaxis of rotation, the yoke assembly including a bearing surfaceconfigured to contact the second end portions of the plurality ofpistons, wherein the bearing surface of the yoke assembly is configuredto rotate about a yoke assembly axis of rotation synchronously with thecylinder block.
 2. The axial piston device of claim 1, wherein the yokeassembly axis of rotation intersects with a bearing surface plane thatis coincident with the bearing surface at a bearing plate central point,wherein the bearing plate central point is offset from the intersectionpoint between the yoke assembly axis of rotation and the cylinder blockaxis of rotation, wherein the offset is in the direction of the secondend portion of the housing along the yoke assembly axis of rotation, andwherein the bearing plate central point is offset from the cylinderblock axis of rotation.
 3. The axial piston device of claim 1, furthercomprising a retainer configured to engage the second end portions ofthe pistons and limit the axial motion of the pistons, wherein theretainer is a plate that includes an aperture of which the pistonsextend through, the retainer being bolted to the yoke assembly.
 4. Theaxial piston device of claim 1, wherein the yoke assembly includes anangled plate that rotates on a bearing assembly and a bearing plate thatinterfaces with the angled plate.
 5. The axial piston device of claim 1,wherein the second end portion of the pistons includes a conical headportion that defines an annular retaining collar.
 6. The axial pistondevice of claim 1, wherein the axial piston device is a hydraulic pump.7. An axial piston device comprising: a housing including a first endportion and a second end portion and including a low-pressure fluidinlet and a high-pressure fluid outlet at the first end portion of thehousing; a cylinder block rotatably positioned within the housingincluding a first end portion and a second end portion, the first endportion of the cylinder block being in the first end portion of thehousing and the second end portion of the cylinder block being in thesecond end portion of the housing, the cylinder block including aplurality of cylindrical bores that extend from the first end portion tothe second end portion of the cylinder block; a drive shaft including afirst end portion that extends inside of the housing and is configuredto drive the rotation of the cylinder block within the housing, thedrive shaft defining a cylinder block axis of rotation; a plurality ofpistons, each piston including a first end portion and a second endportion, each piston being positioned within a cylindrical bore suchthat the piston can reciprocate within the cylindrical bore axiallyalong the longitudinal axis of the piston, the first end portion of thepistons being positioned in the first end portion of the cylinder block,and the second end portion of the pistons extending out of the secondend portion of the cylinder block; an angled plate located in the secondend portion of the housing, the angled plate being inclined relative toa plane that is perpendicular to the cylinder block axis of rotation; abearing assembly provided between the angled plate and the second endportion of the housing enabling the angled plate to rotate about anangled plate axis of rotation; a bearing plate secured to the angledplate, the bearing plate configured to contact with the second endportion of the plurality of pistons; a retainer configured to engage thesecond end portions of the pistons and limit the axial motion of thepistons; and wherein the angled plate, the bearing plate, and theretainer are configured to rotate synchronously with the cylinder block.8. The axial piston device of claim 7, wherein the retainer is a platethat includes an aperture of which the pistons extend through, theretainer being fixed to the angled plate.
 9. The axial piston device ofclaim 7, wherein the bearing plate is retained by the angled plate. 10.The axial piston device of claim 7, further comprising a pin that limitsrelative rotation between the bearing plate and the angled plate. 11.The axial piston device of claim 7, wherein the second end portion ofthe piston includes a conical shape.
 12. The axial piston device ofclaim 7, wherein the second end portion of the piston includes a conicalshape wherein the face of the cone defines a curved profile.
 13. Theaxial piston device of claim 7, wherein the second end portion of thepiston includes an annular collar that engages the retainer.
 14. Theaxial piston device of claim 7, wherein the second end portions of thepiston are configured to trace elliptical circles on the bearing plate.15. The axial piston device of claim 7, wherein the angle of the angledplate is fixed.
 16. The axial piston device of claim 7, wherein therotational speed of the drive shaft varies in order to vary the flow ofthe pump.
 17. The axial piston device of claim 7, wherein the second endportion of the piston translates radially relative to the bearing platewhen the cylinder block rotates.
 18. The axial piston device of claim 7,wherein the intersection of the projection of the cylinder block axis ofrotation and the projection of the angled plate axis of rotation iswithin the planes defined by a top surface of the retainer and a bottomsurface of the retainer.
 19. The axial piston device of claim 7, whereinthe angled plate axis of rotation intersects with a bearing surfaceplane coincident with an exposed face of the bearing plate at a bearingplate central point that is offset from the intersection point betweenthe angled plate axis of rotation and the cylinder block axis ofrotation, wherein the offset is in the direction of the second endportion of the housing along the angled plate axis of rotation.
 20. Theaxial piston device of claim 7, wherein the angled plate axis ofrotation intersects with a bearing surface plane coincident with anexposed face of the bearing plate at a bearing plate central point,wherein the bearing plate central point is offset from the cylinderblock axis of rotation.